1. Field of the Invention
This invention relates to multicomponent alloys for uses in hydrogen storage, and rechargeable hydrogen storage electrode applications. More particularly, the invention relates to rechargeable batteries comprising a nickel-hydride, or silver-hydride couple in which the negative electrode is made of a hydride/hydrogen storage alloy.
2. The Related Art
Sapru et. al. in U.S. Pat. No. 4,551,400 and Rechman et al. in U.S. Pat. No. 4,716,088 reported a rechargeable hydride battery using a pseudo TiV2-type hydrogen storage alloy as the active material of the negative electrode. Their alloys, the V-based alloys: Ti-V-Ni, Ti-Zr-V-Ni and Ti-Cr-V-Ni, each have a short cycle life, high self-discharge rate, and/or are very difficult to activate. Venkatesan et al. in U.S. Pat. No. 4,728,586, and Fetcenko et al. in U.S. Pat. Nos. 5,096,667, 5,104,617 and 5,238,756 disclose a Ti-Zr-V-Ni-Cr-based alloy for the hydride electrode. This kind of alloy still has some weaknesses. The alloy disclosed in these patents contains Ti+Zr from 16.5 at. % to 37.9 at. % and V+Ni from 34.8 to 70.98 at. %. As a result, as given in their examples, the alloys disclosed contain a substantial amount of expensive vanadium metal and have a high corrosion rate in an alkaline medium. All above prior arts do not teach the use and the benefits of niobium (Nb) metal in a hydrogen storage alloy. No information is given in regarding how to use any element selected from the group of: B, Hf, Sc, Zn, Ag, Sb, W, Sn, N, O, Ge, Ga, the alkali metals, P, and S in an alloy. The addition of a suitable amount of these elements has many advantages. Gamo et al in U.S. Pat. No. 4,946,646 disclose hydrogen storage alloys with the general formula, AB.sub.a, where A is at least one element selected from the group consisting of Zr, Ti, Hf, Ta, Y, Ca, Mg, La, Ce, Pr, Mm, Nb, Nd, Mo, Al and Si; B is at least one element selected from the group consisting of Ni, V, Cr, Mn, Fe, Co, Cu, Zn, Al, Si, Nb, Mo, W, Mg, Ca, Y, Ta, Pd, Ag, Au, Cd, In, Sn, Bi, La, Ce, Mm, Pr, Nd, Th and Sm; provided that A and B are different from each other, and a is from 1.0 to 2.5. Although Gamo lists 162 alloys, there are only nineteen alloys which consist of eighteen 5-element alloys and one 6-element alloy. These 19 alloys are all Zr-based containing at least 30 at. % of Zr. Gamo teaches four classes that are also all Zr-based alloys: (1) ZrV.sub.b Ni.sub.c, (2) ZrMo.sub.d Ni.sub.e, (3) Zr.sub.f V.sub.g Ni.sub.h M.sub.i, where M is at least one element selected from a group of 27 elements without Ti; (4) A'B'.sub.j Ni.sub.k, where A' is Zr or a mixture of at least 30 at. % of Zr and the balance of at least one element selected from the group of Ti, Hf, Al and Si; ZrMn.sub.n Cr.sub.o Ni.sub.p is the only subclass given in this class. Other that the above Zr-based alloys, Gamo does not teach a specific quidance for the selection of A from the 16 elements and B from the 31 elements. Specifically, Gamo does not teach a specific quidance to formulate a non-Zr-based alloy which has 5 or more than five elements. Gamo does not teach the use of niobium (Nb) metal and its benefits in a hydrogen storage alloy. As with vanadium metal, Zr is also relatively expensive. Therefore, a Zr-based hydrogen storage alloy has a high cost. In addition, the Zr-based hydrogen storage alloy/hydirde electrode is very difficult to activate and an insoluble oxide layer forms easily on the surface. Therefore, the charging efficiency and rate capabilty are very poor. Consequently, the sealed battery made has a high internal pressure and short cycle life.
Hong in U.S. Pat. Nos. 4,849,205 and 5,006,328 disclosed hydride storage electrode alloys: (1) Ti-Zr-Ni-Cr-M alloy, (2) Ti-Cr-Zr-Ni-V-M alloy, (3) Ti-Zr-V-Ni-M alloy, (4) Ti-Mn-V-Ni-M alloy, where M is an element selected from Al, Si, Fe, Co, Cu, Nb, Ln (rare earth metal) and M is less than 6.25 at. %. In addition, Hong teaches a method to develop an alloy for hydrogen storage and hydride electrode applications. Hong does teach the use of Nb. However, little or no information is given in regarding how to use any element selected from the group of: B, Hf, Sc, Zn, Sb, W, Sn, N, O, Ge, Ga, the alkali metals, P, and S in an alloy. The addition of a suitable amount of these elements has many advantages.
To solve the problems, the present invention provides new alloys for hydrogen storage and particularly for rechargeable hydride electrode and batteries applications.